Anyway, on the ground we settled with 25kgs in the main and no captions, which I found to be a bit strange as I would have thought we might have seen one or the other of the cautions by now.
It could take 2 to 4 min for the caution to come after the pump started to run dry..
As for the decrease of maintank after selecting the XFER pumps off, there was a plausible explanation in the EC135 thread by "yellowbird135". To prove that, someone should leave the XFER pumps off after engine start and have a look whether the supply tank is decreasing adhoc or still the maintank at first ....
skadi